Copy prebuilt objects to the intermediates directory

Copy prebuilt objects to the intermediate directory so that their
output file name matches the module name.  This simplifies using
the clang crt objects, whose input names vary by architecture,
in the musl sysroot genrule.

Bug: 216192129
Test: m checkbuild
Change-Id: I467d699f718e2cc5c6bf0a5c35820dedd51c5930